Nonlinear Magneto-optic Effects with Ultranarrow Widths

Several dispersionlike features in the magnetic field dependence of the nonlinear magneto-optic effect were observed in an experiment performed on rubidium atoms contained in a vapor cell with antirelaxation coating. The narrowest feature has effective resonance width $\gamma =g\mu \Delta B_z\approx 2\pi \times 1.3\mathrm{Hz}$, where $\Delta B_z\approx 2.8\mu \mathrm{G}$ is the peak-to-peak separation. The observed nontrivial dependence of the magneto-optic effect on transverse magnetic fields is discussed. The results of this work may be applied to low-field magnetometry, to parity and time reversal invariance violation experiments, etc.